Jacksonville Jaguars running back Leonard Fournette (27) jumps over defenders while running for yardage during the second half of an NFL football game, Sunday, Oct. 15, 2017, in Jacksonville, Fla. The Rams beat the Jaguars 27-17. (AP Photo/Stephen B. Morton)

Jacksonville Jaguars running back Leonard Fournette (27) is helped off the field after injuring his ankle during the second half of an NFL football game against the Los Angeles Rams, Sunday, Oct. 15, 2017, in Jacksonville, Fla. The Rams beat the Jaguars 27-17. (AP Photo/Stephen B. Morton)

Los Angeles Rams quarterback Jared Goff looks for a receiver against the Jacksonville Jaguars during the first half of an NFL football game, Sunday, Oct. 15, 2017, in Jacksonville, Fla. (AP Photo/Stephen B. Morton)

Los Angeles Rams head coach Sean McVay washes his team play against the Jacksonville Jaguars during the first half of an NFL football game, Sunday, Oct. 15, 2017, in Jacksonville, Fla. (AP Photo/Phelan M. Ebenhack)

Jacksonville Jaguars running back Leonard Fournette, right, runs past Los Angeles Rams linebacker Alec Ogletree (52) on his way to a 75-yard touchdown during the first half of an NFL football game, Sunday, Oct. 15, 2017, in Jacksonville, Fla. (AP Photo/John Raoux)

Jacksonville Jaguars running back Chris Ivory (33) celebrates his 22-yard touchdown on a pass play against the Los Angeles Rams with teammate fullback Tommy Bohanon (40) during the first half of an NFL football game, Sunday, Oct. 15, 2017, in Jacksonville, Fla. (AP Photo/Stephen B. Morton)

Jacksonville Jaguars running back Chris Ivory, left, celebrates as he crosses the goal line in front of Los Angeles Rams safety John Johnson III (43) during the first half of an NFL football game, Sunday, Oct. 15, 2017, in Jacksonville, Fla. (AP Photo/Stephen B. Morton)

JACKSONVILLE, Fla. — There is an unwritten rule in football. It’s not widely known, mind you. But it’s a biggie. Failure to adhere is not recommended.

“You should never lose a game if you ever score on special teams,” said Rams outside linebacker Connor Barwin, sternly.

He was speaking from a Rams locker room that was as happy as it was hot and sticky after the team’s gut-check 27-17 win over the Jacksonville Jaguars on Sunday.

There was a clear and indisputable reason why, too.

“They scored twice,” an appreciative Barwin reminded everyone.

“They” would be the Rams special teams, a unique group of overachievers and tough guys and young players biding their time on the grunt units until a bigger role on offense or defense opens up. Roles that may or may not be granted them, for that matter.

And they are coached by John Fassel, one of the more beloved assistants in the NFL, who teaches up his units like no one’s business. Year in and year out. Over and over and over.

And on a hot, humid late afternoon in Jacksonville, Fassel and his devoted pupils were the difference between the Rams beginning their long odyssey away from Los Angeles by tucking a big win under their pillow or crying into it after swallowing another frustrating loss.

“They came up huge for us,” Barwin said.

Pharoh Cooper got it started with a 103-yard touchdown return of the opening kickoff.

And Cory Littleton and Malcolm Brown ended it, first by Littleton roaring through the Jaguars defensive line to block a punt by Brad Nortman and then Brown picking the ball up and rumbling 8 yards into the end zone for a touchdown.

“I saw the ball flying and my teammates helped me make the play and get into the end zone,” Brown said. “I appreciate all their help, and I definitely wouldn’t have made it in there by myself.”

Littleton and Brown’s tag-team touchdown put the Rams up 24-14 in the second quarter. And while 10 points isn’t a big cushion in the grand scheme of things, against a Jaguars team that prefers to play from ahead by taking leads and then milking them for all their worth behind spectacular rookie running back Leonard Fournette and a ball-hawking defense, 10 points must have seemed like Mount Everest.

The Jaguars aren’t very good when they have to re-write their game plan and turn things over to struggling quarterback Blake Bortles. The fourth-year quarterback is prone to making mistakes, especially when getting leaned on too heavily to make something happen or carry a team from behind.

The Rams special teams put Bortles in that position. And the Rams made him pay by stiffening after a rough first quarter and eventually slamming the door on the smashmouth Jaguars.

Doing so took the pressure off Jared Goff and the offense, which had trouble all afternoon putting together extended drives. Although, when they absolutely needed to, Goff and the offense came up with a 12-play march that erased five minutes from the clock, forced the Jaguars to use all three timeouts, and then turned things over to another special teams ace – kicker Greg Zuerlein – for 29-yard field goal to essentially put the game away.

Cooper to Littleton to Brown to Zuerlein.

They might not ring many bells across the NFL.

But on Sunday, they rang loud and clear for the Rams.

“Basically we came out with a mindset that our special teams was going to make big plays in this game,” Littleton said.

Said Rams coach Sean McVay: “( Special teams) ended up winning the game for us,”

In doing so, the Rams took another dynamic step in the right direction by matching their win total (four) of last year with 10 games still remaining while closing in on being a fairly complete team in all phases.

One that can win while looking good, bad, and even ugly.

The latter being the case on Sunday when the Rams offense managed to find its way into the end zone just once, done in by a horrid 4-of-13 third-down conversion rate — but still emerged victorious because other phases of the team stepped up to compensate.

“Obviously, you never want to do what we did offensively tonight,” Goff said. “I don’t know what we did on third down but I know it wasn’t very good. For those guys, the rest of the guys, to be able to pick us up and really win the game for us is why we won the game tonight.”

And that’s an important development for a young team still trying to find its way back to relevancy.

The Rams haven’t had a winning season in 13 years. That’s a long time to go without finishing a year with more wins than losses, and you would probably need multiple hands to count the many games they lost over the years on afternoons that played out similarly to Sunday’s.

On the road against a good, solid team. Big-time struggles offensively crossing the goal line. A close game. Little margin for error. And plenty of chances to finally crack.

The Rams of last year would have melted Sunday. They would have figured out a way to lose. As they did over and over and over in a miserable year that resulted a coaching change and sweeping personnel improvements.

That didn’t happen on Sunday. And on a day in which nothing much exciting happened in a win no one will particularly remember in the days and weeks ahead, that was extraordinarily significant.

Good teams figure out ways to win rather than lose.

The Rams, it seems, are growing up before our very eyes.

“Credit to our players. I think they just continue to show character, and continue to fight,” said McVay. “Sometimes things don’t always go our way, we’ve had a lot of adversity. But I think when you saw today, offense not really playing quite as well as we would like, defense and special teams picked up their performance, and it’s about winning as a football team, and that’s what we were able to do, and we’ve got to continue to improve in all three phases.”